Automatic control method for growing single-crystal neck portions
AssigneeShin-Etsu Handotai Co., Ltd.
InventorKenji Araki
Life of this patent
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Abstract
The method automatically controls the growing of a single-crystal neck portion by the CZ method. The speed of pulling up the crystal is adjusted so that the crystal diameter control deviation becomes closer to zero. Combinations of the crystal diameter control deviation .DELTA.D being large or small and the pulling-up speed V being high or low are employed as fuzzy inference conditions. According to such conditions, a correction value for the power supplied to a melt heater 18 is calculated, based on the fuzzy inference.
Claims6
An automatic control method for growing a single-crystal neck portion between an initial point and a cone portion by employing the CZ method in order to remove dislocation, said automatic control method comprising the steps of:
- adjusting the pulling-up speed of the seed crystal so that a control deviation of the crystal diameter becomes closer to zero;
- calculating a correction value for the amount of power supplied to a melt heater, based on fuzzy inference, according to fuzzy inference conditions which are combinations of the crystal diameter control deviation (.DELTA.D) being large or small and the pulling-up speed (V) being high or low;
- and
- correcting the power supplied to the heater, by using the correction value.
Dependencies are inferred from the claim text.